Coatings containing plastic polymeric pigments

ABSTRACT

A light weight coating comprising a convenient binder such as starch and small colorless plastic, polymeric particles which remain discrete and retain a diameter of about one wavelength of visible light. The coating, prepared by dispersing the plastic, polymeric particles in an aqueous media containing the binder, may then be applied to a paper substrate in a conventional manner.

ilnited States Patent 1191 11 1 fifiwfi Heiser 1*Dec. W, 1974 [54]COATINGS CONTAINING PLASTIC 3,311,582 3/1967 Sparks et al. 260/29.4 L MEPIGMENTS 3,578,493 5/1971 Smith t 117/155 3,591,412 7/1971 Smit 117/155X [75] Inventor: Edward J. Heiser, Midland, Mich. [73] Assignee: The DowChemical Company, FOREIGN PATENTS OR APPLICATIONS Midland, Mich. 813,5485/1959 Great Britain.... 117/155 1,043,541 91966 G tB 't' 117155 Notice:The portion of the term of this tea n am patent subsequent to Sept. 27,1983, has been disclaimed. Primary Examiner-William D. Martin AssistantExaminer-M. R. Lusignan [22] Flled' July 1972 Attorney, Agent, orFirm-W. M. Yates; M. S. Jenkins [21] Appl. No.: 268,897

Related US. Application Data 57 ABSTRACT [63] Continuation-impart ofSer. No. 732,100, May 27, 1963 A light weight coating comprising aconvenient binder such as starch and small colorless plastic, polymericg i 'i 117/ 6 z ig ia particles which remain discrete and retain adiameter I] f 1 2 l of about one wavelength of visible light. Thecoating, [58] Flam of Search 117/155 prepared by dispersing the plastic,polymeric particles 260/17'4 S R0 in an aqueous media containing thebinder, may then 5 References Cited gzrapplied to a paper substrate in aconventional man- UNITED STATES PATENTS 2,976,182 3/1961 Caldwell et a1.117/1355 21 iClaims, No Drawings COATINGS CONTAINING PLASTIC POLYMERICPIGMENTS CROSS REFERENCES TO RELATED APPLICATIONS This invention is acontinuation-in-part of application Ser. No. 732,100 filed May 27, 1968now US. Pat. No. 3,779,800, patented Dec. 18, 1973.

BACKGROUND OF THE INVENTION This invention relates to lightweight papercoatings having high opacity and visual gloss. More particularly,itrelates to lightweight coatings containing discrete plastic, polymericparticles having diameters in the range from about 0.3 to about 0.8micron.

Most paper surfaces require a coating in order to have good printingqualities and sufficient opacity or hiding power. Conventional papercoatings contain inorganic pigments such as kaolin clay or titaniumdioxide to give the coated substrate the opacity required. Theseinorganic pigments substantially increase the coating weight which inturn increase the cost of mailing substrates so coated.

Paper coatings which contain bubbles as substitutes for inorganicpigments have been described in US. Pat. No. 3,108,009. These coatingsare prepared by dispersing a high boiling immiscible liquid in thebinder media and then evaporating the dispersed liquid after the coatinghas been applied to the substrate. It is desirable in the exercise ofthis method to recapture the evaporated liquid in order to reduce thecosts of the coating. Also, according to this method it is preferable toapply a layer of varnish to the coating containing the air spaces tomake the surface more suitable for printing.

Paper containing expanded microspheres of plastics has been described inUS. Pat. No. 3,293,144, but these expanded microspheres are considerablylarger than a wavelength of visual light. Generally this kind of paperis used primarily in areas where a high degree of opacity is notrequired.

SUMMARY OF THE INVENTION An object of this invention is to provide alight weight coating which upon application to a paper substrate yieldsa surface which has printing qualities comparable to a surface coatedwith an inorganic pigment.

Another object is to produce a coating which upon application to thepaper substrate yields a level surface having a high visual gloss andbrightness. An even further object is to produce a coating having ahigher degree of resistance to blistering than papers coated withmineral pigment, particularly when printed by web offset printingprocesses using heat set inks.

Other objects and advantages of the invention will be evident from thefollowing description.

The objects of this invention have been accomplished by applying a novelcoating to a suitable substrate, said coating comprising a bindingamount of a suitable binder and an opacifying amount of a pigment, atleast a portion of which is in the form of discrete, substantiallyspheroidal, plastic, polymeric particles having an average diameter inthe range from about 0.3 micron to about-0.8 micron. An opacifyingamount of the pigment is that amount which imparts a degree of opacitycomparable to that obtained in conventional paper coatings usinginorganic materials such as clay as pigment. A binding amount of binderis that amount which binds the pigment to the coated! paper substratesuch that the pigment is not removed from the coated paper during normalhandling and/or further processing, e. g.. printing. The plastic,polymeric particles (hereinafter referred to as plastic particles) aresubstantially insoluble in the binder at temperatures necessary tofinish the coated surface. The plastic particles also remain discreteand retain an average diameter in the range from about 0.3 to about 0.8micron during the finishing process. The portion of plastic particles isan amount effective to provide a coating which is lighter in weight and-/or has better opacity, brightness, gloss, or printing qualities such asgloss ink holdout, uniform ink receptivity or blister resistance than dosimilar coatings employing the same binder and containing only inorganicmaterials such as clay as pigment.

DESCRIPTION OF PREFERRED EMBODIMENTS The discrete plastic particlesuseful as part or all of the pigment in coating compositions of thisinvention comprise any non-film forming organic polymer which iswater-insoluble and is insoluble in the particular binder to be used inthe coating composition. It is therefore understood that any polymerhaving the critical physical characteristics described herein servessuitably as the plastic portion of the pigment for the purposes of thisinvention. Preferred polymers are thermoplastic organic polymers.Especially preferred polymers are also classified as resinous and aresubstantially colorless.

In order that the plastic particle retain the discretecharacternecessary to give optimum light scattering (opacity), theparticular polymer chosen must be nonfilm forming at the temperaturesand pressures selected to dry or finish the coated surface. By non-filmforming, it is meant that the dispersed plastic particles do notcoalesce to form a film at ambient temperature and at temperatures andpressures selected to dry or finish the coated article. While suchtemperature requirement varies with the type of finishing method used,it is preferred that the polymer in the form of the discrete, plasticparticles not be film forming at temperatures of F or less if thecoated. surface is to be finished by processes such as calendering orsuper calendering. In order to realize substantially improved gloss, itis sometimes desirable that the plastic particles at the surface of thecoating be flattened or even fused to some degree by the calendering orsuper calendering process. However, the fusion or coalescence of thediscrete plastic particles throughout the coating must be avoided;otherwise the light scattering properties (opacity) of the coatedsurface will be reduced sub stantially. Accordingly, polymers preferredfor use as the plastic particles have a Vicat Softening Point, asdefined and determined by ASTM Dl52565-T, of greater than about 140F. Anespecially preferred class of polymers includes polymers which arepredominantly hydrocarbon. As an additional requirement in order toavoid fusion or coalescence, it is necessary that plastic particles notbe dissolved or softened by the particular binder chosen.

Representative polymers which are suitable for the plastic particlesinclude the non-film forming, waterinsoluble, addition polymers ofpolymerizable ethyllenically unsaturated monomers such as themonovinylidene aromatic monomers, saturated esters of a,B-ethylenicallyunsaturated carboxylic acids, ethylenically unsaturated esters ofnon-polymerizable carboxylic acids, ethylenically unsaturated nitriles,aliphatic a-monooleflns, and other polymerizable and copolymerizableethylenically unsaturated monomers. It is understood that in order to besuitable the monomer or monomers selected in preparation of the plasticparticle must polymerize or copolymerize to form a nonfilm forming,water-insoluble polymer or copolymer as defined hereinbefore.

Exemplary monomers which are suitable employed alone or in combinationwith other monomers include such monovinylidene aromatic monomers as thecarbocyclic types, e.g., styrene, a-methyl styrene, armethylstyrene,ar-methoxystyrene, ar-hydroxymethyl styrene, ar-t-butyl styrene,ar,ar-dimethylstyrene, archlorostyrene, ar,ar-dichlorostyrene,ar-ethylstyrene, ar-cyanostyrene, ar-bromostyrene, ar-ethoxystyrene,ar-chloro-ar-methylstyrene, ar,ar-difluorostyrene, and vinylnaphthalene, and the heterocyclic varieties, e.g., vinyl pyridine. Bymonovinylidene is meant that to an aromatic ring in each molecule ofmonomer is attached one radical of the formula,

wherein R is hydrogen or lower alkyl, e.g., alkyl having I to 4 carbonatoms such as methyl, ethyl, n-propyl, nbutyl and iso-butyl. Alsoincluded are the saturated esters of a,,8-ethylenically unsaturatedcarboxylic acids which polymerize to form non-film forming,waterinsoluble polymers such as methyl methacrylate, chloroethylmethacrylate, 2-butyl methacrylate, 3,3- dimethylbutyl methacrylate,3,3-dimethyl-2-butyl methacrylate, ethyl methacrylate, isobutylmethacrylate, isopropyl methacrylate, phenyl methacrylate, butylchloroacrylate, cyclohexyl chloroacrylate, ethyl chloroacrylate, methylchloroacrylate, 2-chloroethyl methacrylate, isopropyl chloroacrylate,isobutyl chloroacrylate and other such esters, particularly the alkylesters wherein the alkyl moiety has from 1 to carbon atoms and the acidmoiety has from 3 to 8 carbon atoms. Exemplary ethylenically unsaturatedesters of non-polymerizable carboxylic acids which polymerize to formnon-film forming, water-insoluble polymers are vinyl benzoate, vinylar-toluate, vinyl ar-ethylbenzoatae, allyl ar-ethylbenzoate, vinyltrimethylacetate, vinyl trichloroacetate and other such esters whereinthe unsaturated ester moiety has from 2 to 14 carbon atoms and the acidmoiety has from 2 to 12 carbon atoms. Other exemplary monomers includeacrylonitrile, methacrylonitrile, fumaronitrile and other ethylenicallyunsaturated nitriles having not more than 12 carbon atoms and vinylicmonomers such as vinyl chloride, vinyl pyrrolidone, vinyl carbazole andthe like.

Lesser amounts, such as less than about 45 weight percent based on thepolymer, of other ethylenically unsaturated monomers which normallypolymerize to form film-forming polymers (so-called soft monomers) aresuitably copolymerized with the foregoing hard monomers. Examples ofsuch monomers include conjugated aliphatic dienes such as 1,3-butadiene,isoprene, 2-chloro-l,3-butadiene and other such dienes having not morethan 14 carbon atoms; alkyl acrylates such as methyl acrylate, ethylacrylate, propyl acrylate, n-butyl acrylate, isobutyl acrylate, amylacrylate, lauryl acrylate, isoamyl acrylate, Z-ethylhexyl acrylate,octyl acrylate, and other such acrylates having alkyl moieties of notmore than 18 carbon atoms; unsaturated esters of saturated carboxylicacids such as vinyl acetate, vinyl propionate, vinyl butyrate, allylacetate and other such esters having not more than 18 carbon atoms;esters and half esters of a,B-ethylenically unsaturated polycarboxylicacids, e.g., dimethyl fumarate, diethyl maleate, methyl ethyl fumarate,ethyl hydrogen maleate, dioctyl fumarate and the like; aliphaticmonoolefins such as ethylene, propylene and butene-l; othercopolymerizable vinyl monomers containing a single polymerizableethylenically unsaturated group such as vinyl fluoride, vinylidenechloride and vinylidene fluoride. Maximum concentrations of thesemonomers are governed primarily by the temperatures to be reached by thecoating during the coating process and the degree to which a particularmonomer lowers the softening point of the resulting copolymer. Forillustration, if a copolymer of styrene and butadiene is to be used asthe polymer in the plastic particles, butadiene normally is not presentin the copolymer in amount more than about 20 weight percent. If,however, the styrene/butadiene copolymer has more than the normal amountof crosslinking, butadiene may be present in concentration greater than20 weight percent with the maximum concentration of butadiene beingdependent on the actual degree of crosslinking. Similarly, homopolymersof such monomers as ethylene may be rendered non-film forming andtherefore suitable by introduction of crosslinking. Increasedcrosslinking is usually promoted by irradiation or by use of a suitablecrosslinking agent such as unsaturated polyester or polyethylenicallyunsaturated monomer. in amounts up to about 15 weight percent based onthe polymer of the plastic particles. Exemplary polyethylenicallyunsaturated monomers include divinyl benzene, trivinyl benzene, divinylnaphthalene, and the like. In regard to the use of the aforementionedsoft monomers, use in any concentration is suitable provided that theresultant polymer is non-film forming as required in the practice ofthis invention.

In addition to the foregoing monomers, other monomers which may also becopolymerized constituents of the polymeric pigment area,,B-ethylenically unsaturated carboxylic acids including both monoandpolycarboxylic, e.g., dicarboxylic, acids, such as acrylic aacid,methacrylic acid, itaconic acid, fumaric acid, maleic acid andanhydride, citraconic acid and anhydride, aconitic and other such acids.Maximum concentrations of these acid comonomers in the polymeric pigmentare limited by the degree to which they promote water solubility of thepolymer. Since the plastic particles must be water-soluble, the acidcomonomers are generally employed in concentrations not greater than .25weight percent of the polymeric pigment, although somewhat higherconcentrations of acid comonomer may be used if the polymer iscrosslinked or pH of the dispersing medium is controlled.

Other special purpose monomers such as the hydroxy alkyl acrylates, e.g., hydroxyethyl acrylate and hydroxypropyl acrylate and sulfo esters ofa,B-ethylenically unsaturated carboxylic acids, e.g., 2-sulfoethylacrylate, 2-sulfoethyl methacrylate are also suitably employed in thepolymer of the plastic particles, usually in amounts less than about 8weight percent based on the polymer.

The foregoing polymers are given as an illustrative sample of the totalnumber of suitable polymers. For the purposes of this invention, plasticparticles of any polymer which is water-insoluble and non-film formingcan be suitably employed provided that the particles are discrete andhave average diameter as specified hereinbefore.

Preferred addition polymers used in the plastic particle are polymerscomprising from about 40 to 100 weight percent, advantageously fromabout 75 to about 99 weight percent, of one or more of theaforementioned ethylenically unsaturated monomers which homopolymerizeto form non-film forming polymers, from about to about 45 weightpercent, advantageously from about 0 to about 20 weight percent on oneor more of the aforementioned soft monomers and from about 0 to about 15weight percent, advantageously from about 1 to about 5 weight percent,of one or more copolymerizable oz,,B-ethylenically unsaturatedcarboxylic acids, preferably those having 3 to 8 carbon atoms. Of thepreferred addition polymers, polymers comprising from about 40 to 100weight percent of polymerized monovinylidene aromatic carbocyclicmonomers and from 0 to about 60 weight percent of ethylenicallyunsaturated monomers copolymerized therewith in which from 0 to aboutweight percent of the polymer comprises copolymerized afi-ethylenicallyunsaturated carboxylic acid. Especially preferred copolymers arecopolymers comprising from about 50 to 100 weight percent, mostadvantageously from about 75 to about 99 weight percent, ofmonovinylidene carbocyclic aromatic monomers, e.g., styrene andar-(tbutyl) styrene, from 0 to about 49 weight percent, mostbeneficially from 0 to about weight percent, of a,B-ethylenicallyunsaturated nitrile such as acrylonitrile and methacrylonitrile, andfrom about 0 to about 5 weight percent, most beneficially from about 1to about 4 weight percent, of a,-,8-ethylenically unsaturated carboxylicacid such as acrylic acid, methacrylic acid and itaconic acid includingcombination thereof. Examples of such especially preferred copolymersare styrene/acrylic acid copolymers, styrene/acrylonitrile/itaconic acidcopolymers, styrene/methacrylic acid copolymers, and t-butylstyrene/acrylonitrile/acrylic acid copolymers. Also preferred are vinylchloride/acrylic acid copolymers and vinyl benzoate/acrylic acidcopolymers. ln the foregoing preferred copolymers, it is sometimesbeneficial to copolymerize from about 1 to about 15 weight percent ofpolyethylenically unsaturated monomer such as divinyl benzene therewith.

As suitable alternative to foregoing addition polymers, non-film formingcondensation polymers which are water-insoluble and insoluble in thebinder are also advantageously employed. Exemplary suitable condensationpolymers include: polyesters, e.g.,

poly(ethylene tercphthalate),

poly( propylene terephthalate),

poly(ethylene 1,5-naphthalate),

poly(ethylene 2,7-naphthalate),

poly(ethylene isophthalate),

poly[ethylene 4,4'-(2,2-butylidene) dibenzoate]; polycarbonates e.g.,

poly(4,4'-butylidenediphenylene carbonate),

poly(4,4-isopropylidenediphenylene carbonate); polyanhydrides, e.g.,

poly(4,4'-methylenebenzoic anhydride),

poly(isophthalic anhydride); polyamides, e. g.,

poly(hexamethylene pimelamide),

poly(hexamethylene azeloamide),

poly( hexamethylene adipamide poly(7-aminoenanthic acid).

The specific gravity of the polymers used in the practice of theinvention usually is within the range from about 0.9 to about 1.6,preferably within the range from about 0.9 to about 1.4. In order thatthe coating be considerably lighter in weight than coatings containinginorganic pigments, it is preferable that the particles be made from apolymer which is predominantly hydrocarbon since such polymers have. aspecific gravity generally less than about 1.2. The refractive index ofpreferred polymers is generally in the range of from about 1.2 to about1.7, especially from about 1.4 to about 1.6.

In addition to being composed of non-film forming polymer as set forthhereinbefore, it is critical that the plastic particles have an averagediameter in the range of from about 0.3 to about 0.8 micron. By averagediameter is meant the number average particle diameter. Preferably, theplastic particles have a particle diameter distribution typical of mostessentially monosperse or monomodal systems. Suitably, however, theplastic particles have a sufficient number of particles having diameterwithin and near the range from about 0.3 to about 0.8 micron that theplastic particles are as efficient as an opacifier as clay on an equalvolume basis. Preferably at least 50 volume percent of the plasticparticles are within the range from about 0.2 to about 0.9 micron, mostpreferably at least volume percent are within said range. It has beenobserved that differences in refractive index and differences inparticle shape, particle surface characteristics and/or particle packingcan cause different samples of plastic particles having essentially thesame average particle diameter to possess different pigmentingefficiencies (e. g., opacifying' efficiencies). It is generally found,however, that samples of non-film forming plastic particles havingaverage diameters within the aforementioned range have pigmentingefficiencies which are about equal to or even better than the pigmentingefficiency of clay on a volume basis. Clay is the pigment most commonlyemployed in paper coatings, and therefore is useful in setting astandard of acceptability for a pigment in the paper coating art.

These particles may be prepared by emulsion polymerization of a suitablemonomer or mixture of such monomers or by emulsifying a suitable polymerproduced by another method such as bulk or solution polymerization. Forexample, in a typical emulsion polymerization procedure, the monomericcomponents of the polymer are dispersed in an aqueous solutioncontaining an emulsifier and an electrolyte. A watersoluble free radicaltype catalyst is added to the dispersion to initiate the polymerization,and the mixture isagitated until the polymerization is completed. Thesize of the particles is controlled by known means such as varying theamount of emulsifier and electrolyte in the system and/or time ofaddition of same. For example, as the amount of emulsifier is increased,the particle size is decreased. The amount of emulsifier and electrolyteneeded to give a particle having the proper size may vary according tothe particular polymer being formed.

Any binder of a type conventionally employed in aqueous coatingcompositions adapted to a paper coating process to provide an adherent,smooth, layer suitable for printing is suitable for the purposes of thisinvention. Exemplary suitable binders include the natural binders suchas modified starch, soy bean protein and casein and commonly knownsynthetic binders.

Suitable modified starch binders include oxidized, enzyme converted,cationic, thermal-converted and hydroxy-ethylated varieties.

Suitable synthetic binders include any waterdispersible organicsynthetic polymer which is filmforming at ambient temperature and whichis a nonsolvent for the plastic pigment. Preferred synthetic binders arewater-insoluble addition polymers having an apparent second ordertransition temperature (Ti) of not more than about 30C, preferably fromabout 40C to about C. Exemplary preferred binders are latexes or aqueousdispersions of polymers such as polymers of conjugated dienes such asbutadiene, chloroprene and isoprene, e.g., styrene/butadiene copolymer,butadiene/acrylonitrile copolymer, styrene/isoprene copolymer,butadiene/methyl methacrylate copolymer, polybutadiene, polyisoprene,polychloroprene and the like; polymers of alkyl esters ofa,,B-ethylenically unsaturated carboxylic acids such as acrylate esters,e.g., ethyl acrylate/acrylic acid copolymers, methyl acrylate/itaconicacid copolymers, ethyl acrylate/hexyl acrylate/methacrylamidemethacrylamide copolymers, alkyl acrylate/vinyl acetate copolymers,styrene/alkyl acrylate copolymers; vinyl chloride/vinylidene chloridecopolymers; and the like. Suitable binders include aqueous dispersionsor solutions of such polymers as polyvinyl acetate, polyvinyl alcohol,vinylidene chloride copolymers, ethylene/vinyl acetate copolymers,cellulosics such as methyl cellulose and carboxymethyl cellulose andothers commonly used as pigment binders, particularly in conventionalpaper coating formulations. Also suitable are mixtures of two or morenatural binders, two or more synthetic binders and mixtures of one ormore synthetic binders with one or more natural binders.

The paper coating of the invention is advantageously prepared bydispersing the pigment at least a portion of which is plastic particlesin an aqueous medium containing the binder. Preferably the plasticparticles are added in the form of a latex in the dispersing step.Suitable binder/pigment ratios require sufficient binder to bind thepigment to the paper such that pigment is not removed from coated papersubstrate during normal handling, e.g., printing, etc. Suitable ratioalso requires sufficient pigment (inclusive of plastic particles andoptional inorganic pigment) to opacify the coated paper substrate.Generally ratios of binder to pigment (inclusive of plastic particlesand optional inorganic pigment) are in the range of about 1.3 to about12 volume parts of binder to about 38.8 volume parts of pigment.Preferred ratios are in the range from about 6 to about 10 volume'partsof binder to about 38.8 volume parts of pigment. In a coating of astarch binder having a specific gravity of 1.5 and a pigment having aspecific gravity of about 1.05, e.g., a pigment consisting of nonporouspolymerized styrene particles, the range of suitable volume ratios fromabout 1.3 to about 12 volume parts of binder to 38.8 volume parts ofpigment corresponds to a weight ratio of about 2 to about 17 weightparts (dry basis) of binder to 40.7 parts (dry basis) of pigment. Inorder to completely eliminate effect of change of specific gravity ofeither or both of binder and pigment, the ratio of binder to pigment isstated on a volume basis.

It should be clearly understood that the pigments employed in the papercoating invention include a combination of inorganic pigment and theplastic particles. In such combination the plastic particles are used inan amount which is effective to lower coating weight and- /or to enhancethe coating properties of gloss, pick resistance, printing qualities,brightness or the like as compared to a coating containing only theinorganic pigment as pigment. Preferably, the plastic particlesconstitute at least about 1 volume percent of the total pigment.

Exemplary inorganic pigments which are suitable for the purposes of thisinvention include clays such as kaolinite and other materials such astitanium dioxide, kieselguhr, calcium carbonate, calcium sulfate,calcium sulfite, barium sulfate, blanc fixe, satin white, aluminumhydrates and zinc pigments, e.g., zinc oxide, zinc sulfide andlithopone. More generally, any inorganic pigment which is a satisfactorypigment in conventional paper coatings is a suitable inorganic pigmentin the practice of this invention.

The coating is applied to a paper substrate by a conventional techniquesuch as air knife, trailing blade, inverted blade, roll coaters and thelike.

After the coating is applied, the surface of the substrate is dried andoften is then finished by calendering or supercalendering. It iscritical that the temperature of the coating does not exceed thesoftening point of the plastic particles, otherwise the particles willlose their discrete character or proper size and shape. When thisoccurs, the opacity and brightness of the coated surface dropssubstantially.

The drying times required by the coating containing the plasticparticles are not as long as those required by coatings containing theinorganic pigments. Also the paper substrate coated with the plasticparticles has a better finish and higher visual gloss than paper coatedwith an inorganic pigment.

Where the solvent sensitivity of particles of a specific plastic polymerpresents a problem, a coating containing the plastic particles may beapplied to the paper substrate as a base coating and such base coatingis subsequently coated with a coating containing an inorganic pigmentwhich is not as sensitive to solvent. Since by that procedure much lesscoating containing the inorganic pigment will be required to yield asurface with the desired gloss and opacity, the total coating weight isusually reduced about 25 percent. Solvent sensitivity can also beovercome by introducing some crosslinking into the polymer of plasticparticles.

The following examples illustrate the invention, but are not to beconstrued as limiting its scope. Except as indicated, all parts andpercentages are by weight. Weight parts and volume parts are calculatedon dry solids basis.

EXAMPLE 1 A blend is prepared of an aqueous dispersion of oxidizedstarch and a latex of polystyrene, the particles of which having anaverage diameter of 0.5 micron as determined by electron microscope, ina ratio of 15 parts (10.5 volume parts) of starch and 38.5 parts (38.8volume parts) of polystyrene particles calculated on a dry basis, andthe solids content of the blend is adjusted to 43.5 percent. The mixtureis then applied with a drawdown bar to a polished black glass plate andair dried at room temperature. Five square inches of the applied coatingis removed and weighed. This weight is compared with the weight of acoating applied in the same manner but containing kaolin clay having asolids content of 51.5 percent. The clay coating has a ratio of 10volume parts oxidized starch to 38.8 volume parts clay. In each testsufficient coating was applied to achieve a brightness of 70. Brightnessis determined by TAPPI Test Method T452-M58. The results of thiscomparison are shown in the following table.

A coating color, hereinafter designated II, is made according to Example1, containing 10 parts (7.05 volume parts) on a dry basis of oxidizedstarch and 38.5 parts (388 volume parts) on dry basis of latex ofpolystyrene having an average diameter of 5,000 Angstroms is applied toa paper substrate by a puddle type trailing blade, double coating withdrying in a circulating oven after each coat. A coating color (not anexample of the invention), hereinafter designated II(C), containing 100parts (38.8 volume parts) on dry basis of kaolin clay andlS parts (10.0volume parts) on dry basis of oxidized starch is similarly applied to asecond portion of the same paper substrate. The results are shown in thefollowing table for comparison purposes.

Coating Properties (supercalendered 6 nips at 1200 pli). 75 Gloss 43 56Brightness 74.5

Opacity 91.6

TABLE Il-Continued COAT DATA K&N ink, Drop 34.3 52

[GT Dry Pick 270 280 No. 6 ink (FL/min.)

Coating Weight Lbs/ream (25X38500) 8.3 3.9

*Not an example of the invention.

Gloss is determined by TAPPI Test Method T480TS-65.

Brightness is detennined by TAPPI Test Method T452-M-58.

"Opacity is determined by TAPPI Test Method T425-M-60.

K&N ink is measured according to TAPPI Test Method RC 19.

TOT Picking Resistance is measured according to TAPPI Test Method T499su 64.

EXAMPLE 3 A single base coating color of composition II of Example 2 isapplied to a portion of the same paper substrate used in Example 2 by apuddle type trailing blade. This base coating is dried and then a singlefinish coating of composition II(C) of Example 2 is applied to the drybase coating by a puddle type trailing blade. The results, obtained bythe same testing methods used in Example 2, are shown in the followingtable.

*The same testing methods used in Example 2 are used in this example.

EXAMPLE 4 Substantially the same results are obtained when for thepolystyrene pigment of Example 2 there is substituted the same quantityof a copolymer of 92 percent of styrene,'6 percent of acrylonitrile, and2 percent of itaconic acid in the form of approximately sphericalparticles having an average diameter of about 5,000 Angstroms.

EXAMPLE 5 Substantially the same results are obtained when for thepolystyrene pigment of Example 2, there is substituted the same quantityof a copolymer of 89 percent by weight of styrene, 6 percent by weightof acrylonitrile, 3 percent by weight of B-hydroxyethyl acrylate and 2percent by weight of itaconic: acid in the form of approximatelyspherical particles having an average diameter of about 5,000 Angstroms.

EXAMPLE 6 Several coating compositions are prepared using starch asbinder and styrene polymer particles as pigment. The particles of thecoating compositions have iii average diameters as indicated in TableIV. The several coating compositions have a ratio of 38.5 weight parts(38.8 volume parts) of polymer particles to weight parts (7 volumeparts) of starch. The weight parts are measured on a dry basis. Equalportions of the compositions are applied to black glass plates in amountsufficient to form films having wet thicknesses of 1 /2 mils and towhite glass plates in amounts sufficient to form films having wetthicknesses of 3 mils and are air dried at room temperature.Brightnesses for the coated black glass plates and coated white glassplates are determined according to TAPPI Test Method T452M-58. Fivesquare inch portions of the coatings applied to the black glass platesare removed and weighed. Scattering coefficients for the coatings arethen calculated from the values of brightness and coating weights usingthe equation:

Scattering coefficient ST/220 A wherein ST is a value read directly fromMitton- Jacobsen Graphs plotting the ST value against reflectance of thecoating over black and white glass plates and A is the weight in gramsof a five square inch of coating. Reflectance is equal to 0.01 Xbrightness. The Mitton-Jacobsen Graphs are described in the OfficialDigest, September 1963, pp. 885-911.

The scattering coefficients for the coatings are recorded in Table IV.

TABLE IV Not an example of the invention. "Not measurable using theMilton Jacobson Graphs. l St -st \rene. lA-itaeunie acid,VCN-aerylunitrilc. DVBaliviuyl hell/1311i.

As evidenced by the scattering coefficients for Run Nos. 1, 7, 8. 9 and10 of Table IV, coatings of latex of polymer particles having averagediameters outside the range of 0.3 to 0.8 micron have substantiallylower scattering coefficients than do coatings containing particleshaving average diameter within the specified range and consequently havepoorer opacity or hiding at equivalent coating weights.

EXAMPLE 7 Several blends are prepared of hydrorxyethylated starch and alatex of non-film forming styrene/acrylic acid (97/3) copolymer havingan average particle size of 0.49 micron and a second order glasstransition temperature of 105C in varying ratios calculated on solidsbasis as recorded in Table V. The solids contents of the blends areadjusted to 40 weight percent. The scattering coefficients for theseveral blends are determined according to the method describedinExample 6 and are recorded in Table V. IGT- Picking Resistance was alsodeterined for the several blends in accordance with TAPPI Test MethodT499 su 64 and the results are recorded in Table V.

TABLE V Polymer to lGT Picking Run Starch Ratio Scattering Resistance,No. Wt. Pts Vol. Pts Coefficient ft/min A* 38.5:1 38.8:073 0.506 B38.5:3 38.8221 0.422 (No.1 ink) C 38.515 38.8:3.5 0.412 255 (No.2 ink) D38.5210 38.817 0.285 (No.6 ink) E 38.5115 38.81105 0.193 305 (No.8 ink)F 385:]? 38.81119 0.168 310 (No.8 ink) G* 38.5:20 38.8:14 0.106 345(No.8 ink) *Not an example of the invention. "Coating was so weak that avalue could not he obtained.

A coating composition containing Kaolin clay and the starch binder in avolume ratio of 38.8 volume parts of clay to 7 volume parts of starchbinder has a scattering coefficient of 0.168.

EXAMPLE 8 Several blends are prepared of ethylated starch and latexes ofnon-film forming vinyl benzoate/acrylic acid (97/3) copolymer havingaverage particle sizes as indicated in Table VI in ratio of 7 volumeparts of starch (binder) to 38.8 volume parts of copolymer particles(pigment). The solids contents of the blends ar adjusted to 40 weightpercent and the scattering coefficients for the blends are determinedaccording to the procedure of Example 6. The results are recorded inTable VI.

Two blends are prepared of ethylated starch and la texes of non-filmforming methyl methacrylate/butyl acrylate/methacrylic acid/acrylic acid(81/15/3/1) copolymer having average particle sizes as indicated inTable VI] in ratio of 7 volume parts of starch (binder) to 38.8 volumeparts of copolymer particles (pigment) calculated on a solids basis. Thesolids contents of the blends are adjusted to 40 weight percent and thescattering coefficients for the blends are determined according to theprocedure of Example 6. The results are recorded in Table V11.

TABLE V11 Average Particle Scattering Run No. Diameter, MicronCoefficient Not an example of the invention.

EXAMPLE 1O Several blends are prepared of hydroxyethylated coefficientswere determined for this blend in accordance with the procedure ofExample 6. The results are recorded in Table VIII.

For purposes of comparison, a clay coating (Run No. C) is preparedhaving a ratio of 38.8 volume parts of clay to 7 volume parts of starch.The scattering coefficient is determined and recorded in Table VIII.

TABLE V111 Average Monomeric Compo Diameter Run Type of sition of Latexof Scattering No. Pigment Polymer, wt% Plastic Coefiicient Particles,

Micron 2O 1 Plastic 100 Styrene 0.44 0.225 2 Plastic 97 Vinyl Toluene/ 3Acrylic Acid 060 0.199 3 Plastic 97 t'butylstyrene/ 3 Acrylic Acid 0.710.255 25 4 Plastic tbutylstyrene/ 47 Acrylonitrile/ 3 Acrylic Acid 0.440.236 5 Plastic Acrylonitrile/ 37 Styrene/ 3 Acrylic Acid 0.83 0.192 6Plastic 92 Styrene/ 3O 6 Acrylonitrile/ 2 ltaconic Acid 0.43 0.212 7Plastic Styrcnc/ l5 Acrylic Acid 0.51 0.214 (7* Clay 0.168

Nut an example of the invention 35 EXAMPLE 1 1 Several blends areprepared each using one of a variety of binders as specified in Table IXand a latex of non-film forming styrene/acrylic acid (97/3) copolymer,the particles of which have an average diameter of 0.49 micron, in aratio of 10 weight parts of binder to 38.5 weight parts of copolymerparticles. Scattering coefficients for the blends are determinedaccording to procedure used in Example 6. The results of thesedeterminations are recorded in Table IX.

For purposes of comparison, blends of the same binders and clay in ratioof 15 weight parts of binder to weight parts of clay are prepared ascomparative blends. Scattering coefficients of these comparative blendsare determined in accordance with the procedure of Example 6. Theresults are recorded in Table IX in parentheses adjacent to thecorresponding blend of the binder and latex.

TABLE IX Scattering Coefficients Run Binder Plastic Clay No. Particles lA Hydroxyethylated Starch 0.250 (0.131) B rotein 0.249 (0.176) C MethylCellulose 0.424 (0.155) D Styrene/Butadiene Copolymer 0.267 (0.141 EPolyvinyl acetate 0.278 (0.149) F Polyvinyl alcohol 0.194 (0.081) GCasein 0.258 (0.181) H Eth 1 acrylate/acrylic aci copolymer 0.277(0.154)

EXAMPLE 12 Several coating compositions are prepared using a binder asindicated in Table X and styrene/acrylic acid copolymer (97/3) particlesas the pigment. The particles of the coating compositions have averagediameters as indicated in Table X. The several coating compositions havea ratio of 38.8 volume parts of pigment to 7 volume parts of binder. Thescattering coefficients of the coating compositions are measured in themanner set forth in Example 6, and the results are recorded in Table X.

Scattering coefficients of compositions havingclay as pigment andpigment to binder ratio on a volume basis equivalent to the precedingcompositions are also determined and recorded in Table X.

TABLE X Pi ent un verage Scatterin Coefficient No. Type Diameter Starch(a) SlB Acetate(c) Latex(b) 1* Plastic 0.14 0.105 0.137 0.093

Particles 2 Plastic 0.37 0.235 0.289 0.290

Particles 3 Plastic 0.41 0.266 0.334 0.306

Particles 4 Plastic 0.47 0.267 0.333 0.292

Particles 5 Plastic 0.53 0.259 0.316 0.301

Particles 6 Plastic 0.77 0.227 0.261 0.346

Particles D* Clay 0.168 0.186 0.179

"Not an example 01 the invention (a)hydroxyethylatcd starch(b)styrene/hutadiene latex (cipolyvinyl acetate latex EXAMPLE 13 Severalcoating compositions are prepared using a starch binder and a pigment ofclay, styrene/acrylic acid copolymer of Example 7 or combination thereofas indicated in Table XI. The coating compositions are tested asindicated in Table XI and the results are recorded.

TABLE XI Run Clay/Plastic Particle/Starch Solids Viscosity( 1 ScatteringCoating Weight(3),

No. Ratio, volume parts Wt cps Coefiicient(2) lbs/book ream Brightness(4) 1* l00/0/l7.2 55.0 1370 0.162 10.0 76.6 2 97.5/2.5/17.2 54.7 13700.173 9.6 76.9 3 95/5/l7.2 54.3 1270 0.167 9.6 76.8 4 90/10/172 53.61270 0.178 9.5 77.0 5 85/15/172 52.9 1430 0.184 9.3 78.0 6 75/25/17251.4 1350 0.200 8.6 78.3 7 50/50/172 47.2 1320 0.224 7.5 79.6 825/75/172 42.1 1 0.255 6.0 80.9 9 10/90/172 38.6 1130 0.262 5.0 81.5

TABLE Xl -Continued Run C lay/Plastic Particle/Starch Solids Viscosity(1 Scattering Coating Weight(3), No. Ratio, volume parts Wt cpsCoefficient(2) lbs/book ream Brightness (4) Run K&N lnk(), 70 dropOpacity(6) lGT Pick Resistancefl), ft/min. No.

' Not an example of the invention.

( I) Brookl'reld viscosity at room temperature and 20 rpm.

(2) Scattering Coeflicicnt determined by procedure of Example 6.

(3) Coating weight in pounds per book ream [500 pages X 38'') per bookream].

(4) TAP?! Test Method 'l'452-M 58.

(5) 'l'APPl Test Method RC 19.

(6) 'I'APPI lest Method '1425-M-60.

(7) 'l'APPl Test Method T499 so (14 using A" Tension. 35 kilogramspressure and No. 5 ink except in Run No. 10 the value reported inparentheses represents test with No. (i ink.

about 0.3 to about 0.8 micron, said portion of plastic particlesconstituting at least about 1 volume What is claimed is: l. A coatedpaper having printing applied to a surfins, vinyl fluoride, vinylidenechloride and vinylidene fluoride and not greater than 25 weight percentof a,B-ethylenically unsaturated carboxylic acid; and

face thereof comprising 25 percent based on total pigment and beingsufficient A. a paper substrate having intimately adhered to impartimproved coating properties as compared thereto; to a coating containingonly inorganic pigment, B. an improved coating comprising a bindingamount said polymer being a substantially colorless, therof a binder andan opacifying amount of a pigment, moplastic, addition polymer of fromabout 40 to provided that (l) the ratio of binder to pigment is 100weight percent of monovinylidene aromatic in the range from about 1.3 toabout 12 volume monomer, from 0 to 60 weight percent of copolyparts ofbinder to about 38.8 olu e parts O P gmerizable monomeric selected fromthe group conment; and at least a Portion of Said P g is sisting ofconjugated aliphatic diene, alkyl acryn the form of discrete,Substantially sp lates, unsaturated esters of saturated carboxylicWaterand binder-inwluble, non-film g, acids, esters and half esters ofa,B-ethylenically un- Polymeric PlaStic Particles of an Organic P ysaturated polycarboxylic acids, aliphatic monoole- Sald Particles havingan average diameter of from fins, vinyl fluoride, vinylidene chlorideand vinyliabout 0.3 to about 0.8 micron, said portion of plasdene fl idand mgethylenicany unsaturated tic particles constituting at least about1 volume carboxylic i i i h polymer f O to about p t based on total Piand being Sufficient 15 percent is afi-ethyleni'cally unsaturatedcarboxt0 lmpart i p a a PTOPeTtICS a mp ylic acid and the binder isselected from the group a f g comammg y morgamc Plgmem, consisting ofstarch, modified starch, soybean pro- Sald orgalllc Polymer g a Polymerof tein, casein, polymers of conjugated dienes, and monovmylldenearomatic monomer; polymers of alkyl esters of afi-ethylenically unsatb.less than about weight percent of copolymer- 45 mated carboxylic acids,polyvinyl acetate, polyw zable monomer selectedfrorn the group consistlal ohol, vinylidene chloride copolymers, of conlugated allphatlc dlene,alkyl F y t ethylene/vinyl acetate copolymers and cellulosicsunsaturated esters of saturated carboxylic acids, and mixtures thereof;and esters and half esters of a,B-ethylenically unsatuprinting appliedto Said coating rated polycarboxylic acids, aliphatic monoole- 5 3. Acoated paper having printing applied to a surface thereof, comprising A.a paper substrate having intimately adhered thereto;

B. an improved coating comprising a binding amount ment, and (2) atleast a portion of said pigment is in the form of discrete,substantially spheroidal, waterand binder-insoluble, non-film forming,polymeric plastic particles of an organic polymer, said particles havingan average diameter of from Prmtmg apphed to f q t of a binder and anopacifying amount of a pigment, A Coated Papa? havmg prmtmg apphed to aprovided that (l) the ratio of binder to pigment is face thereof,Comprlsmg in the range from about 1.3 to about 12 volume A. a papersubstrate having mtlmately adhered parts of binder to about & volumeparts f t 6O ment and (2) at least a portion of said pigment is anmllproved coatmg Q P a bmdmg amount in the form of discrete,substantially spheroidal, Ofa blndel and an opaclfymg amount ofaPlgmentt waterand binder-insoluble, non-film forming, Provided that thefatlo 0f bmdef t0 Plgment polymeric plastic particles having an averagediamin the range from abou 3 to about 12 Volume eter of from about 0.3to about 0.8 micron, said Parts of binder to about Volume Parts Of Pportion of plastic particles constituting at least about 1 volumepercent based on total pigment and being sufficient to impart improvedcoating properties as compared to a coating containing only inorganicpigment, said organic polymer consisting essentially of (a) from about40 to about weight percent of monovinylidene carbocyclic aromaticmonomers; (b) from to 45 weight percent of an ethylenically unsaturatedsoft monomer selected from the group consisting of conjugated aliphaticdienes, alkyl acrylates, unsaturated esters of saturated carboxylic acidwhich polymerize to form film-forming polymers, esters and half estersof afi-ethylenically unsaturated polycarboxylic acids, vinylidenechloride, and mixtures thereof (c) from O to about 49 weight percent ofa,B-ethylenically unsaturated nitrile and (d) from 0 to about weightpercent of afi-ethylenically unsaturated carboxylic acid monomer; and

C. printing applied to said coating.

4. The coated paper of claim 3 wherein the ratio of binder to pigment isin the range of from about 6 to about 10 volume parts of binderto 38.8volume parts of pigment.

5. The coated paper according to claim 2 wherein the polymer consistsessentially of from about 75 to 100 weight percent of monovinylidenecarbocyclic aromatic monomer, from 0 to about weight percent ofacrylonitrile and from about 0 to about 5 weight percent ofa,B-ethylenically unsaturated carboxylic acid selected from the groupconsisting of acrylic acid, methacrylic acid, itaconic acid, maleicacid, maleic anhydride, fumaric acid and mixtures thereof and the binderis selected from the group consisting of starch, modified starch,casein, soybean protein, styrene/- butadiene copolymer,butadiene/acrylonitrile copolymer, butadiene/methyl methacrylatecopolymer, vinyl chloride/vinylidene chloride copolymer, polychloroprenecopolymer, polybutadiene copolymer, polyvinyl acetate and mixturesthereof.

6. The coated paper according to claim 3 wherein the polymer consistsessentially of from about 75 to about 100 weight percent ofmonovinylidene carbocyclic aromatic monomer from about 0 to about 20weight percent of a,B-ethylenically unsaturated nitrile, from 0 to about20 weight percent of ethylenically unsaturated soft monomer selectedfrom group consisting of conju gated aliphatic dienes, alkyl acrylates,and mixtures thereof and from 0 to about 5 percent of a,/3-ethylenicallyunsaturated carboxylic acid monomer having from 3 to 8 carbon atoms andthe binder is selected from the group consisting of starch, oxidizedstarch, enzyme converted starch, cationic starch, thermalconvertedstarch, hydroxyethylated starch, soybean protein and casein,sytrene/butadiene copolymer, butadiene/acrylonitrile copolymer,styrene/isoprene copolymer, butadiene/methyl methacrylate copolymer,polybutadiene, polyisoprene, polychloroprene, ethyl acrylate/acrylicacid copolymers, methyl acrylate/itaconic acid copolymers, ethylacrylate/hexyl acrylate/- methacrylamide copolymers, alkylacrylate/vinyl acetate copolymers, and styrene/alkyl acrylatecopolymers, polyvinyl acetate, polyvinyl alcohol, ethylene/vinyl acetatecopolymers, methyl cellulose and carboxymethyl cellulose and mixturesthereof.

7. The coated paper according to claim 5 wherein monovinylidenecarbocyclic aromatic monomer is styrene.

8. The coated paper according to claim 5 wherein at least 50 volumepercent of the plastic particles have diameters in the range from about0.2 to about 0.9 micron.

9. The coated paper according to claim 5 wherein the binder is selectedfrom the group consisting of modified starch, polyvinyl acetate andstyrene/butadiene copolymer.

10. The coated paper according to claim 5 wherein the pigment consistsof at least about 1 volume percent of plastic particles and a remainingportion of inorganic pigment.

11. The coated paper according to claim 10 wherein the inorganic pigmentis clay.

12. A coated paper having printing applied thereon, comprising A. apaper substrate having intimately adhered thereto;

B. an improved coating comprising from about 3 to about 17 parts byweight of a binder and 38.5 parts by weight of a pigment, provided thatthe amount of pigment is an opacifying amount and at least a portion ofsaid pigment is in the form of discrete,

"substantially spheroidal, waterand binderinsoluble, non-film forming,polymeric plastic particles of an organic polymer, said particles havingan average diameter of from about 0.3 to about 0.8 micron, said portionof plastic paraticles constituting at least about 1 volume percent basedon total pigment and being sufficient to impart improved coatingproperties as compared to a coating containing only inorganic pigmentand the remaining portion of pigment is inorganic pigment which is asatisfactory pigment in conventional paper coatings, said organicpolymer being a polymer selected from the group consisting ofhomopolymers of monovinylidene aromatic carbocyclic monomer andcopolymers of monovinylidene aromatic carbocyclic monomer and from 0 toabout 5 weight percent of an afiethylenically unsaturated carboxylicacid selected from the group consisting of acrylic acid, methacrylicacid, itaconic acid, maleic acid and fumaric acid, and from 0 to about20 weight percent of a copolymerizable monomer selected from the groupconsisting of butadiene, isoprene, methyl acrylate, ethyl acrylate,propyl acrylate, butyl acrylate, and acrylonitrile; and

C. printing applied to said coating.

13. The coated paper of claim 12v wherein the binder is selected fromthe group consisting of starch, modified starch, soybean protein,casein, polymers of conjugated dienes and polymers of alkyl esters ofa,,8-ethylenically unsaturated carboxylic acids and polyvinyl acetate,polyvinyl alcohol, vinylidene chloride copolymers, ethylene/vinylacetate copolymers and cellulosics and mixtures thereof.

M. The coated paper of claim 12 wherein the binder is selected from thegroup consisting of starch, oxidized starch, enzyme converted starch,cationic starch, thermal-converted starch, hydroxyethylated starch,soybean protein and casein, styrene/butadiene copolymer,butadiene/acrylonitrile copolymer, styrene/isoprene copolymer,butadiene/methyl methacrylate copolymer, polybutadiene, polyisoprene,polychloroprene, ethyl acrylate/acrylic acid copolymers, methylacrylate/itaconic acid copolymers, ethyl acrylate/hexyl acrylate/-methacrylamide copolymers, alkyl acrylate/vinyl acetate copolymers, andstyrene/alkyl acrylate copolymers, polyvinyl acetate, polyvinyl alcohol,ethylene/vinyl acetate copolymers, methyl cellulose and carboxymethylcellulose and mixtures thereof.

15. The coated paper of claim 12 wherein the binder is selected from thegroup consisting of starch, modified starch, casein, soybean protein,styrene/butadiene copolymer, butadiene/acrylonitrile copolymer,butadiene/methyl methacrylate copolymer, vinyl chloride/vinylidenechloride copolymer, polybutadiene copolymer, polychloroprene copolymerand polyvinyl acetate.

16. The coated paper according to claim 12 wherein the pigment consistsof at least about 1 volume percent of plastic particles and a remainingportion of inorganic pigment.

17. The coated paper of claim 15 wherein the inorganic pigment isselected from the group consisting of clay, titanium dioxide,kieselguhr, calcium carbonate, calcium sulfate, calcium sulfite, bariumsulfate, blanc fixe, satin white, aluminum hydrites and zinc pigments.

18. The coated paper of claim 15 wherein the inorganic pigment is clay.

19. The coated paper of claim 15 wherein the monovinylidene aromaticmonomer is styrene.

20. The coated paper according to claim 15 wherein at least volumepercent of the plastic particles have diameters in the range from about0.2 to about 0.9 micron.

21. The coated paper of claim 15 wherein the organic polymer is apolymer consisting essentially of from about to weight percent ofstyrene from 0 to about 20 weight percent of acrylonitrile and fromabout 0 to about 5 weight percent of afi-ethylenically unsaturatedcarboxylic acid selected from the group consisting of acrylic acid,methacrylic acid and itaconic acid.

32 3 UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent3,853,579 Dated Deoember 10, 1974 Invent0r(s) Edward J. Heiser It iscertified that error appears in the above-identified patent and thatsaid Letters Patent are hereby corrected as shown below:

Cover page of the patent under the section "Notice" the date Sept. 27,1983' should read -Dec. 18, l990-.

Column 2, line 32, the word "particle" should read -particles--,

Column 3, line 48, the last word of the line "ar-ethylbenzoatae" shouldread ar-ethylbenzoate-.

Column 4, line 47, the letters "aa-" should read Column 4, line 54, thewords "water-soluble" should read -water-insoluble--..

Column 11, line 58, the word "hydrorxyethylated" should be-hydroxyethylated-.

Column ll, line 68, the word "deterined" should be --determined-.

Signed and sealed this 1st day of April 1975.

(SEAL) Attest:

C. I-IARSHAIL DANE Commissioner of Patents and Trademarks RUTH C, IIASON[attesting Officer

1. A COATED PAPER HAVING PRINTING APPLIED TO A SURFACE THEREOFCOMPRISING A. A PAPER SUBSTRATE HAVING INTIMATELY ADHERED THERETO; B. ANIMPROED COATING COMPRISING A BINDING AMOUNT OF A BINDER AND A OPACIFYINGAMOUNT OF A PIGMENT, PROVIDED THAT (1) THE RATIO OF BINDER TO PIGMENT ISIN THE RANGE FROM ABOUT 1.3 TO ABOUT 12 VOLUME PARTS OF BINDER TO ABOUT38.8 VOLUME PARTS OF PIGMENT; AND (2) AT LEAST A PORTION OF SAID PIGMENTIS IN THE FORM OF DISCRETE, SUBSTANTIALLY SPHERIODAL, WATER-ANDBINDER-INSOLUBLE, NON-FILM FORMING, POLYMERIC PLASTIC PARTICLES OF ANORGANIC POLYMER, SAID PARTICLES HAVING AN AVERAGE DIAMETER OF FROM ABOUT0.3 TO ABOUT 0.8 MICRON, SAID PORTION OF PLASTIC PARTICLES CONSTITUTINGAT LEAST ABOUT 1 VOLUME PERCENT BASED ON TOTAL PIGMENT AND BEINGSUFFICIENT TO IMPART IMPROVED COATING PROPERTIES AS COMPARED TO ACOATING CONTAINING ONLY INORGANIC PIGMENT, SAID ORGANIC POLYMER BEING APOLYMER OF A. MONOVINYLIDENE AROMATIC MONOMER; B. LESS THAN ABOUT 45WEIGHT PERCENT OF COPOLYMERIZABLE MONOMER SELECTED FROM THE GROUPCONSISTING OF CONJUGATED ALIPHATIC DIENE, ALKYL ACRYLATES, UNSATURATEDESTERS OF SATURATED CARBOXYLIC ACIDS, ESTERS AND HALF ESTERS OFA,B-ETHYLENICALLY UNSATURATED POLYCARBOXYLIC ACIDS, ALIPHATICMONOOLEFINS, VINYL FLUORIDE, VINYLIDENE CHLORIDE AND VINYLIDENE FLUORIDEAND C. NOT GREATER THAN 25 WEIGHT PERCENT OF A,B-ETHYLENICALLYUNSATURATED CARBOXYLIC ACID; AND C. PRINTING APPLIED TO SAID COATING. 2.A coated paper having printing applied to a surface thereof, comprisingA. a paper substrate having intimately adhered thereto; B. an improvedcoating comprising a binding amount of a binder and an opacifying amountof a pigment, provided that (1) the ratio of binder to pigment is in therange from about 1.3 to about 12 volume parts of binder to about 38.8volume parts of pigment, and (2) at least a portion of said pigment isin the form of discrete, substantially spheroidal, water- andbinder-insoluble, non-film forming, polymeric plastic particles of anorganic polymer, said particles having an average diameter of from about0.3 to about 0.8 micron, said portion of plastic particles constitutingat least about 1 volume percent based on total pigment and beingsufficient to impart improved coating properties as compared to acoating containing only inorganic pigment, said polymer being asubstantially colorless, thermoplastic, addition polymer of from about40 to 100 weight percent of monovinylidene aromatic monomer, from 0 to60 weight percent of copolymerizable monomeric selected from the groupconsisting of conjugated aliphatic diene, alkyl acrylates, unsaturatedesters of saturated carboxylic acids, esters and half esters of Alpha ,Beta -ethylenically unsaturated polycarboxylic acids, aliphaticmonoolefins, vinyl fluoride, vinylidene chloride and vinylidenefluoride, and Alpha , Beta -ethylenically unsaturated carboxylic acid inwhich polymer from 0 to about 15 percent is Alpha , Beta -ethylenicallyunsaturated carboxylic acid and the binder is selected from the groupconsisting of starch, modified starch, soybean protein, casein, polymersof conjugated dienes, and polymers of alkyl esters of Alpha , Beta-ethylenically unsaturated carboxylic acids, polyvinyl acetate,polyvinyl alcohol, vinylidene chloride copolymers, ethylene/vinylacetate copolymers and cellulosics and mixtures thereof; and C. printingapplied to said coating.
 3. A coated paper having printing applied to asurface thereof, comprising A. a paper substrate having intimatelyadhered thereto; B. an improved coating comprising a binding amount of abinder and an opacifying amount of a pigment, provided that (1) theratio of binder to pigment is in the range from about 1.3 to about 12volume parts of binder to about 38.8 volume parts of pigment and (2) atleast a portion of said pigment is in the form of discrete,substantially spheroidal, water- and binder-insoluble, non-film forming,polymeric plastic particles having an average diameter of from about 0.3to about 0.8 micron, said portion of plastic particles constituting atleast about 1 volume percent based on total pigment and being sufficientto impart improved coating properties as compared to a coatingcontaining only inorganic pigment, said organic polymer consistingessentially of (a) from about 40 to about 100 weight percent ofmonovinylidene carbocyclic aromatic monomers; (b) from 0 to 45 weightpercent of an ethylenically unsaturated soft monomer selected from thegroup consisting of conjugated aliphatic dienes, alkyl acrylates,unsaturated esters of saturated carboxylic acid which polymerize To formfilm-forming polymers, esters and half esters of Alpha , Beta-ethylenically unsaturated polycarboxylic acids, vinylidene chloride,and mixtures thereof (c) from 0 to about 49 weight percent of Alpha ,Beta -ethylenically unsaturated nitrile and (d) from 0 to about 15weight percent of Alpha , Beta -ethylenically unsaturated carboxylicacid monomer; and C. printing applied to said coating.
 4. The coatedpaper of claim 3 wherein the ratio of binder to pigment is in the rangeof from about 6 to about 10 volume parts of binder to 38.8 volume partsof pigment.
 5. The coated paper according to claim 2 wherein the polymerconsists essentially of from about 75 to 100 weight percent ofmonovinylidene carbocyclic aromatic monomer, from 0 to about 20 weightpercent of acrylonitrile and from about 0 to about 5 weight percent ofAlpha , Beta -ethylenically unsaturated carboxylic acid selected fromthe group consisting of acrylic acid, methacrylic acid, itaconic acid,maleic acid, maleic anhydride, fumaric acid and mixtures thereof and thebinder is selected from the group consisting of starch, modified starch,casein, soybean protein, styrene/butadiene copolymer,butadiene/acrylonitrile copolymer, butadiene/methyl methacrylatecopolymer, vinyl chloride/vinylidene chloride copolymer, polychloroprenecopolymer, polybutadiene copolymer, polyvinyl acetate and mixturesthereof.
 6. The coated paper according to claim 3 wherein the polymerconsists essentially of from about 75 to about 100 weight percent ofmonovinylidene carbocyclic aromatic monomer from about 0 to about 20weight percent of Alpha , Beta -ethylenically unsaturated nitrile, from0 to about 20 weight percent of ethylenically unsaturated soft monomerselected from group consisting of conjugated aliphatic dienes, alkylacrylates, and mixtures thereof and from 0 to about 5 percent of Alpha ,Beta -ethylenically unsaturated carboxylic acid monomer having from 3 to8 carbon atoms and the binder is selected from the group consisting ofstarch, oxidized starch, enzyme converted starch, cationic starch,thermal-converted starch, hydroxyethylated starch, soybean protein andcasein, sytrene/butadiene copolymer, butadiene/acrylonitrile copolymer,styrene/isoprene copolymer, butadiene/methyl methacrylate copolymer,polybutadiene, polyisoprene, polychloroprene, ethyl acrylate/acrylicacid copolymers, methyl acrylate/itaconic acid copolymers, ethylacrylate/hexyl acrylate/methacrylamide copolymers, alkyl acrylate/vinylacetate copolymers, and styrene/alkyl acrylate copolymers, polyvinylacetate, polyvinyl alcohol, ethylene/vinyl acetate copolymers, methylcellulose and carboxymethyl cellulose and mixtures thereof.
 7. Thecoated paper according to claim 5 wherein monovinylidene carbocyclicaromatic monomer is styrene.
 8. The coated paper according to claim 5wherein at least 50 volume percent of the plastic particles havediameters in the range from about 0.2 to about 0.9 micron.
 9. The coatedpaper according to claim 5 wherein the binder is selected from the groupconsisting of modified starch, polyvinyl acetate and styrene/butadienecopolymer.
 10. The coated paper according to claim 5 wherein the pigmentconsists of at least about 1 volume percent of plastic particles and aremaining portion of inorganic pigment.
 11. The coated paper accordingto claim 10 wherein the inorganic pigment is clay.
 12. A coated paperhaving printing applied thereon, comprising A. a paper substrate havingintimately adhered thereto; B. an improved coating comprising from about3 to about 17 parts by weight of a binder and 38.5 parts by weight of apigment, provided that the amount of pigment is an opacifying amount andat least a portion of said pigment is in the form of discrete,substantially spheroidal, water- and binder-insOluble, non-film forming,polymeric plastic particles of an organic polymer, said particles havingan average diameter of from about 0.3 to about 0.8 micron, said portionof plastic paraticles constituting at least about 1 volume percent basedon total pigment and being sufficient to impart improved coatingproperties as compared to a coating containing only inorganic pigmentand the remaining portion of pigment is inorganic pigment which is asatisfactory pigment in conventional paper coatings, said organicpolymer being a polymer selected from the group consisting ofhomopolymers of monovinylidene aromatic carbocyclic monomer andcopolymers of monovinylidene aromatic carbocyclic monomer and from 0 toabout 5 weight percent of an Alpha , Beta -ethylenically unsaturatedcarboxylic acid selected from the group consisting of acrylic acid,methacrylic acid, itaconic acid, maleic acid and fumaric acid, and from0 to about 20 weight percent of a copolymerizable monomer selected fromthe group consisting of butadiene, isoprene, methyl acrylate, ethylacrylate, propyl acrylate, butyl acrylate, and acrylonitrile; and C.printing applied to said coating.
 13. The coated paper of claim 12wherein the binder is selected from the group consisting of starch,modified starch, soybean protein, casein, polymers of conjugated dienesand polymers of alkyl esters of Alpha , Beta -ethylenically unsaturatedcarboxylic acids and polyvinyl acetate, polyvinyl alcohol, vinylidenechloride copolymers, ethylene/vinyl acetate copolymers and cellulosicsand mixtures thereof.
 14. The coated paper of claim 12 wherein thebinder is selected from the group consisting of starch, oxidized starch,enzyme converted starch, cationic starch, thermal-converted starch,hydroxyethylated starch, soybean protein and casein, styrene/butadienecopolymer, butadiene/acrylonitrile copolymer, styrene/isoprenecopolymer, butadiene/methyl methacrylate copolymer, polybutadiene,polyisoprene, polychloroprene, ethyl acrylate/acrylic acid copolymers,methyl acrylate/itaconic acid copolymers, ethyl acrylate/hexylacrylate/methacrylamide copolymers, alkyl acrylate/vinyl acetatecopolymers, and styrene/alkyl acrylate copolymers, polyvinyl acetate,polyvinyl alcohol, ethylene/vinyl acetate copolymers, methyl celluloseand carboxymethyl cellulose and mixtures thereof.
 15. The coated paperof claim 12 wherein the binder is selected from the group consisting ofstarch, modified starch, casein, soybean protein, styrene/butadienecopolymer, butadiene/acrylonitrile copolymer, butadiene/methylmethacrylate copolymer, vinyl chloride/vinylidene chloride copolymer,polybutadiene copolymer, polychloroprene copolymer and polyvinylacetate.
 16. The coated paper according to claim 12 wherein the pigmentconsists of at least about 1 volume percent of plastic particles and aremaining portion of inorganic pigment.
 17. The coated paper of claim 15wherein the inorganic pigment is selected from the group consisting ofclay, titanium dioxide, kieselguhr, calcium carbonate, calcium sulfate,calcium sulfite, barium sulfate, blanc fixe, satin white, aluminumhydrites and zinc pigments.
 18. The coated paper of claim 15 wherein theinorganic pigment is clay.
 19. The coated paper of claim 15 wherein themonovinylidene aromatic monomer is styrene.
 20. The coated paperaccording to claim 15 wherein at least 70 volume percent of the plasticparticles have diameters in the range from about 0.2 to about 0.9micron.
 21. The coated paper of claim 15 wherein the organic polymer isa polymer consisting essentially of from about 75 to 100 weight percentof styrene from 0 to about 20 weight percent of acrylonitrile and fromabout 0 to about 5 weight percent of Alpha , Beta -ethylenicallyunsaturated carboxylic acid selected from the group consisting ofacrylic acid, methacrylic acid and itaconic acid.